Plantar pressure and sole thickness of the forefoot

Selected hallmarks of hallux valgus in older women with symptomatic hallux valgus compared to middle-aged women with and without deformation of the forefoot

The aim of the study was to compare the shape of the feet, the mobility of the metatarsophalangeal and interphalangeal joints and the flexibility of the calf muscles in older women with hallux valgus versus middle-aged women with and without this deformation to identify the presence of features which correlate particularly strongly with hallux valgus, and on which prophylaxis and conservative treatment should focus. The study involved 201 women: 92 aged 60-84 years with hallux valgus of both toes, 78 aged 38-59 with hallux valgus of both toes, and 31 aged 38-57 years with correctly shaped feet. The intensity of pain in the foot, the valgus angle of the big toe and fifth toe, the longitudinal and transverse arches of the foot, the symmetry of foot load with body weight, toe joint mobility and muscle flexibility were analysed. Both groups of women with hallux valgus differed from women with normal feet in the height of the transverse arch, the extent of dorsal extension in the first metatarsophalangeal joint and plantar flexion in the first interphalangeal joint. Older women were additionally characterised by reduced plantar flexion in the metatarsophalangeal joint of the big toe, limited flexibility of the soleus and gastrocnemius muscles as well as less pain in the toe area than in the foot itself. The most characteristic changes which were observed in older women with hallux valgus are a limited range of motion in the MTP and IP joints of the big toe, a reduced transverse arch and increased restriction of calf muscle flexibility.

Relationship Between Plantar Callosity and Foot Deformity in Hallux Valgus Using Weightbearing Computed Tomography

Plantar callosities under lesser metatarsals are often accompanied by the hallux valgus, and the cause of callosity is thought to be associated with the foot deformity, such as the metatarsal length discrepancy, the abnormal metatarsal head height, cavus, flat foot, and rheumatoid conditions. However, it is unclear which variable is most involved in the cause of callosity in hallux valgus deformity. To clarify the factors associated with the callosity with hallux valgus deformity, we conducted multiple image assessments based on weightbearing radiography and computed tomography. A retrospective review was performed based on the collection of clinical records from all patients with hallux valgus treated from 2010 to 2019 in our institution. We measured the hallux valgus angle, intermetatarsal angles, calcaneal pitch angles, talo-first metatarsal angles, metatarsal length, metatarsal head height, first metatarsal pronation angles, and sesamoid position with weightbearing radiography and computed tomography. We analyzed the relation between callosity formation and imaging assessments using univariate and multivariate logistic regression models. Fifty feet were retrospectively evaluated, and multiple logistic analyses by the stepwise method revealed that the first metatarsal-lateral-sesamoid distance was the only radiographical variable associated with callosity formation among all the tested variables (p < .001). As the grade of the callosity became more severe, the lateral shift of the lateral sesamoid increased. The position of the sesamoid bone appears to have a critical role in the assessment and choice of treatment protocols and further research needs to be conducted on the relationship with the position of sesamoid bone to elucidate the mechanism of callus formation.

Standard reference values of weight and maximum pressure distribution in healthy adults aged 18-65 years in Germany

Background

The aim of this study was to collect standard reference values of the weight and the maximum pressure distribution in healthy adults aged 18–65 years and to investigate the influence of constitutional parameters on it.

Methods

A total of 416 healthy subjects (208 male / 208 female) aged between 18 and 65 years (Ø 38.3 ± 14.1 years) participated in this study, conducted 2015–2019 in Heidelberg. The age-specific evaluation is based on 4 age groups (G1, 18–30 years; G2, 31–40 years; G3, 41–50 years; G4, 51–65 years). A pressure measuring plate FDM-S (Zebris/Isny/Germany) was used to collect body weight distribution and maximum pressure distribution of the right and left foot and left and right forefoot/rearfoot, respectively.

Results

Body weight distribution of the left (50.07%) and right (50.12%) foot was balanced. There was higher load on the rearfoot (left 54.14%; right 55.09%) than on the forefoot (left 45.49%; right 44.26%). The pressure in the rearfoot was higher than in the forefoot (rearfoot left 9.60 N/cm², rearfoot right 9.51 N/cm²/forefoot left 8.23 N/cm², forefoot right 8.59 N/cm²). With increasing age, the load in the left foot shifted from the rearfoot to the forefoot as well as the maximum pressure (p ≤ 0.02 and 0.03; poor effect size). With increasing BMI, the body weight shifted to the left and right rearfoot (p ≤ 0.001, poor effect size). As BMI increased, so did the maximum pressure in all areas (p ≤ 0.001 and 0.03, weak to moderate effect size). There were significant differences in weight and maximum pressure distribution in the forefoot and rearfoot in the different age groups, especially between younger (18–40 years) and older (41–65 years) subjects.

Discussion

Healthy individuals aged from 18 to 65 years were found to have a balanced weight distribution in an aspect ratio, with a 20% greater load of the rearfoot. Age and BMI were found to be influencing factors of the weight and maximum pressure distribution, especially between younger and elder subjects. The collected standard reference values allow comparisons with other studies and can serve as a guideline in clinical practice and scientific studies.

Weightbearing Forefoot Axial Radiography - Technical Description and Reproducibility Evaluation

Objective  The present study aims to describe a new weightbearing radiographic method to visualize the heads of the five metatarsals on the coronal plane, evaluating their accuracy through intraclass correlation coefficients.

Methods  The subjects were evaluated, with weightbearing, with the ankle at 20 degrees of plantar flexion and the metatarsophalangeal joints at 10 degrees of extension, positioned on a wooden device. Two independent foot and ankle surgeons evaluated the radiography, with one of them doing it twice, at different moments, achieving an inter and intraobserver correlation, with intraclass correlation coefficients.

Results  We radiographed 63 feet, achieving an interobserver correlation coefficient of the radiographic method for the metatarsal heads heights in the coronal plane of the 1 ^st , 2 ^nd , 3 ^rd , 4 ^th , and 5 ^th metatarsals of, respectively, 0.90, 0.85, 0.86, 0.83, 0.89. The intraobserver correlation coefficient were, respectively, 0.95, 0.93, 0.93, 0.86, 0.92.

Conclusion  Those correlations demonstrate that the method is accurate and can be used to investigate metatarsal head misalignments in this plane.

Repeatability and agreement of ultrasonography with computed tomography for evaluating forefoot structure in the coronal plane

Background

Forefoot structure is important to understand some foot problems such as hallux valgus and metatarsalgia. Ultrasonography (US) is a highly portable, noninvasive, low cost, and fast imaging method, especially when compared to magnetic resonance imaging (MRI), computed tomography (CT), and radiography. As the use of US for evaluating forefoot bony structure has not been validated, except for the presence of synovitis, erosions and bursitis within the forefoot in people with inflammatory arthritis, the purpose of this study was to determine whether US is a reliable method for evaluating forefoot structure.

Methods

Sixty feet (30 women, age = 40.1 ± 11.8 years) were examined by US and CT to assess agreement with CT and repeatability of US evaluation of the 2nd metatarsal head height, length between the medial sesamoid bone and 5th metatarsal head, transverse arch height, transverse arch index, sesamoid rotation angle, and area under the transverse arch. The measurement data were evaluated for agreement with CT using the intra-class correlation coefficient (ICC)_{3, 1}, Pearson correlation coefficient, and Bland-Altman plot, and with ICC_{1, 1} for repeatability.

Results

The ICC_{3, 1} values of 0.78–0.89, Pearson correlation coefficient of 0.78–0.90, and Bland-Altman plots showed almost perfect agreements between the US and CT method for all parameters, except the area under the transverse arch (AUTA). The ICC_{1, 1} also showed perfect agreements (0.84–0.92) between two sets of US measurements in all parameters.

Conclusions

The US evaluation of forefoot structure in the coronal plane showed good agreement with CT and repeatability of two ultrasonograms in adult women. This reliable evaluation method of forefoot structure can contribute to a quick clinical assessment screening for risk factors of foot problems such as hallux valgus and metatarsalgia. However, because of some limitations such as a lack of inter-observer reliability, more research is needed to validate US evaluation of forefoot structure.

Trial registration

The current study (trial registration number: R0297) was approved by the Ethical Committee for Human Experiments of Kyoto University (http://www.ec.med.kyoto-u.ac.jp) on December 3, 2015. The first participant in this study was enrolled on November 17, 2015 and retrospectively registered.

Evaluation of the relationship between the static measurement of transverse arch flexibility of the forefoot and gait parameters in healthy subjects

[Purpose] To investigate the relationship between the static measurement of the transverse arch of the forefoot, using a 3-dimensional (3D) foot scanner, and kinetics and kinematics of gait parameters in the sagittal plane. [Subjects and Methods] Twenty healthy subjects participated in this study. The transverse arch of the forefoot was measured under three conditions as follows: condition 1, sitting; condition 2, standing; and condition 3, foot forward and lower leg tilting anteriorly to the maximum position with heel contact. Gait parameters were recorded using a 3D motion analysis system and force plate. Correlation coefficients between TAF for each comparison of conditions and gait parameters were calculated using the Spearman correlation analysis. [Results] Rates of the transverse arch of the forefoot width and height between condition 2 and condition 3 were significantly correlated with the anterior and posterior component of ground reaction forces, the hip joint extension angle, and the ankle plantar flexion moment. [Conclusion] Our study’s findings indicated that increased stiffness of the transverse arch of the forefoot was related to the increase in ankle plantar moment, and decreased stiffness of the transverse arch of the forefoot was related to the increase in hip joint extension angle during gait.

Does it matter how we measure metatarsal length?

INTRODUCTION

Variations in the relative lengths of the metatarsal bones have been implicated as a cause of forefoot pain. Osteotomies to balance the metatarsal lengths have been described as therapy. Although measurement of metatarsal length is required for these osteotomies, there is no gold standard method to measure it radiologically. We compared the three main radiological methods to measure the second metatarsal length described in the literature.

MATERIALS AND METHODS

Standing dorsoplantar radiographs of 81 feet were measured using the methods described by Coughlin, Maestro and Hardy and Clapham. Bland and Altman's method was used to compare the above techniques for reproducibility and agreement between each method.

RESULTS

The three methods produced markedly different results. Coughlin's and Maestro's methods showed a relative protrusion of the second metatarsal-relatively longer than the first metatarsal by an average of 4 & 3 mm respectively. Hardy and Clapham's method, however, showed a relative retraction of second metatarsal by an average of 1 mm. Both intra-observer and inter-observer errors were smallest for the Coughlin method (the most reproducible) and largest for the Hardy/Clapham method. Significant lack of agreement was found when we compared the 3 techniques with bias for measuring the mean between methods ranging from 1mm to 5.5mm.

CONCLUSIONS

Metatarsal lengths as measured by these three methods can be very variable. Thus their role in planning metatarsal osteotomies and establishing relationship of metatarsal protrusion with metatarsophalangeal joint instability and other similar conditions is questionable and require further studies.

The transverse forefoot arch demonstrated by a novel X-ray projection

OBJECTIVE

Metatarsalgia is often treated by metatarsal osteotomy. Exact knowledge of the normal anatomy of the forefoot is essential for pre-operative planning. The objective of this study was to investigate the forefoot arch during maximal loading in a randomly selected population sample.

METHODS

Two hundred subjects randomly selected from a municipality representative of Denmark were invited to interview and forefoot X-ray examination, including a novel horizontal X-ray projection by which the height of each metatarsal from the floor can be measured under maximal loading.

RESULTS

One hundred and thirty-four subjects (79%) presented themselves for interview and X-ray examination. The study group was representative of the randomly selected population sample in terms of age, sex and incidence of metatarsalgia. The study verified that the interrelated geometry of the metatarsal heads in the AP plane corresponds to a parabola as suggested previously (Le Lièvre's parabola). Also in the horizontal plane, the metatarsal heads generally form an arch, the transverse forefoot arch (TFA). Mean height was 3.91mm (S.E.=0.10). The individual height of the TFA varied from -1 to 10mm and was dependent on the width of the forefoot. The relative height of the arch (arch height divided by forefoot width) was independent of age and sex. A non-significant tendency towards a lower arch among subjects with metatarsalgia was observed.

CONCLUSION

This population study demonstrated that the metatarsal heads constitute arches in both planes (Le Lièvre's parabola in the AP plane and the transverse forefoot arch in the horizontal plane). This knowledge is essential for pre-operative planning in metatarsal osteotomy for metatarsalgia. Formulae for calculating the individual location of each metatarsal head were obtained.

Prediction of peak pressure from clinical and radiological measurements in patients with diabetes

BACKGROUND

Various structural and functional factors of foot function have been associated with high local plantar pressures. The therapist focuses on these features which are thought to be responsible for plantar ulceration in patients with diabetes. Risk assessment of the diabetic foot would be made easier if locally elevated plantar pressure could be indicated with a minimum set of clinical measures.

METHODS

Ninety three patients were evaluated through vascular, orthopaedic, neurological and radiological assessment. A pressure platform was used to quantify the barefoot peak pressure for six forefoot regions: big toe (BT) and metatarsals one (MT-1) to five (MT-5). Stepwise regression modelling was performed to determine which set of the clinical and radiological measures explained most variability in local barefoot plantar peak pressure in each of the six forefoot regions. Comprehensive models were computed with independent variables from the clinical and radiological measurements. The difference between the actual plantar pressure and the predicted value was examined through Bland-Altman analysis.

RESULTS

Forefoot pressures were significant higher in patients with neuropathy, compared to patients without neuropathy for the whole forefoot, the MT-1 region and the MT-5 region (respectively 138 kPa, 173 kPa and 88 kPa higher: mean difference). The clinical models explained up to 39 percent of the variance in local peak pressures. Callus formation and toe deformity were identified as relevant clinical predictors for all forefoot regions. Regression models with radiological variables explained about 26 percent of the variance in local peak pressures. For most regions the combination of clinical and radiological variables resulted in a higher explained variance. The Bland and Altman analysis showed a major discrepancy between the predicted and the actual peak pressure values.

CONCLUSION

At best, clinical and radiological measurements could only explain about 34 percent of the variance in local barefoot peak pressure in this population of diabetic patients. The prediction models constructed with linear regression are not useful in clinical practice because of considerable underestimation of high plantar pressure values. Identification of elevated plantar pressure without equipment for quantification of plantar pressure is inadequate. The use of quantitative plantar pressure measurement for diabetic foot screening is therefore advocated.

Effect of footwear and orthotic devices on stress reduction and soft tissue strain of the neuropathic foot

BACKGROUND

Ground reaction forces from walking result in stress (pressure) and soft tissue strain at the plantar aspect of the foot. Excessive plantar pressure and tissue strain on the insensate foot may lead to ulceration. Our study investigated the effect of therapeutic footwear and custom-made orthotic inserts on pressure and tissue strain along the second ray of the plantar foot, and how these two variables are associated.

METHODS

Twenty subjects (mean age 57.3 [SD 9.3] years, 12 male, 8 female, body mass index 32.5 [SD 7.4] kg/m2) with diabetes mellitus, peripheral neuropathy, and a history of a plantar ulcer participated. Plantar pressure data were recorded during computed tomography scans for four conditions (barefoot, shoe, shoe+total contact insert, and shoe+total contact insert+metatarsal pad). For each condition tested, tissue strain and plantar pressure were determined at the second metatarsal head and at 15 other points along the second ray.

FINDINGS

Differences were noted between the 4 conditions for pressure (P<0.004) and soft tissue strain (P<0.042) at the second metatarsal head. Correlation coefficients demonstrated an association between pressure and strain (Barefoot r=0.81, Shoe r=0.75, Shoe+total contact insert r=0.73, and Shoe+total contact insert+metatarsal pad r=0.44).

INTERPRETATION

Footwear and orthotic devices tested in this study decreased pressure and soft tissue strain at the second ray of the foot, and these two variables were strongly related. A better understanding of the role tissue strain plays in distributing plantar forces may lead to improvements in the design of orthotic devices.